platform/x86:intel/pmc: Enable the ACPI PM Timer to be turned off when suspended

Allow to disable ACPI PM Timer on suspend and enable on resume. A
disabled timer helps optimise power consumption when the system is
suspended. On resume the timer is only reactivated if it was activated
prior to suspend, so unless the ACPI PM timer is enabled in the BIOS,
this won't change anything.

The ACPI PM timer is used by Intel's iTCO/wdat_wdt watchdog to drive the
watchdog, so it doesn't need to run during suspend.

Signed-off-by: Marek Maslanka <mmaslanka@google.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20240812184208.1080710-1-mmaslanka@google.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/platform/x86/intel/pmc/adl.c

@@ -295,6 +295,8 @@ const struct pmc_reg_map adl_reg_map = {
 	.ppfear_buckets = CNP_PPFEAR_NUM_ENTRIES,
 	.pm_cfg_offset = CNP_PMC_PM_CFG_OFFSET,
 	.pm_read_disable_bit = CNP_PMC_READ_DISABLE_BIT,
+	.acpi_pm_tmr_ctl_offset = SPT_PMC_ACPI_PM_TMR_CTL_OFFSET,
+	.acpi_pm_tmr_disable_bit = SPT_PMC_BIT_ACPI_PM_TMR_DISABLE,
 	.ltr_ignore_max = ADL_NUM_IP_IGN_ALLOWED,
 	.lpm_num_modes = ADL_LPM_NUM_MODES,
 	.lpm_num_maps = ADL_LPM_NUM_MAPS,

drivers/platform/x86/intel/pmc/cnp.c

@@ -200,6 +200,8 @@ const struct pmc_reg_map cnp_reg_map = {
 	.ppfear_buckets = CNP_PPFEAR_NUM_ENTRIES,
 	.pm_cfg_offset = CNP_PMC_PM_CFG_OFFSET,
 	.pm_read_disable_bit = CNP_PMC_READ_DISABLE_BIT,
+	.acpi_pm_tmr_ctl_offset = SPT_PMC_ACPI_PM_TMR_CTL_OFFSET,
+	.acpi_pm_tmr_disable_bit = SPT_PMC_BIT_ACPI_PM_TMR_DISABLE,
 	.ltr_ignore_max = CNP_NUM_IP_IGN_ALLOWED,
 	.etr3_offset = ETR3_OFFSET,
 };

drivers/platform/x86/intel/pmc/core.c

@@ -11,6 +11,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/acpi_pmtmr.h>
 #include <linux/bitfield.h>
 #include <linux/debugfs.h>
 #include <linux/delay.h>
@@ -1208,6 +1209,38 @@ static bool pmc_core_is_pson_residency_enabled(struct pmc_dev *pmcdev)
 	return val == 1;
 }
 
+/**
+ * Enable or disable ACPI PM Timer
+ *
+ * This function is intended to be a callback for ACPI PM suspend/resume event.
+ * The ACPI PM Timer is enabled on resume only if it was enabled during suspend.
+ */
+static void pmc_core_acpi_pm_timer_suspend_resume(void *data, bool suspend)
+{
+	struct pmc_dev *pmcdev = data;
+	struct pmc *pmc = pmcdev->pmcs[PMC_IDX_MAIN];
+	const struct pmc_reg_map *map = pmc->map;
+	bool enabled;
+	u32 reg;
+
+	if (!map->acpi_pm_tmr_ctl_offset)
+		return;
+
+	guard(mutex)(&pmcdev->lock);
+
+	if (!suspend && !pmcdev->enable_acpi_pm_timer_on_resume)
+		return;
+
+	reg = pmc_core_reg_read(pmc, map->acpi_pm_tmr_ctl_offset);
+	enabled = !(reg & map->acpi_pm_tmr_disable_bit);
+	if (suspend)
+		reg |= map->acpi_pm_tmr_disable_bit;
+	else
+		reg &= ~map->acpi_pm_tmr_disable_bit;
+	pmc_core_reg_write(pmc, map->acpi_pm_tmr_ctl_offset, reg);
+
+	pmcdev->enable_acpi_pm_timer_on_resume = suspend && enabled;
+}
 
 static void pmc_core_dbgfs_unregister(struct pmc_dev *pmcdev)
 {
@@ -1404,6 +1437,7 @@ static int pmc_core_probe(struct platform_device *pdev)
 	struct pmc_dev *pmcdev;
 	const struct x86_cpu_id *cpu_id;
 	int (*core_init)(struct pmc_dev *pmcdev);
+	const struct pmc_reg_map *map;
 	struct pmc *primary_pmc;
 	int ret;
 
@@ -1462,6 +1496,11 @@ static int pmc_core_probe(struct platform_device *pdev)
 	pm_report_max_hw_sleep(FIELD_MAX(SLP_S0_RES_COUNTER_MASK) *
 			       pmc_core_adjust_slp_s0_step(primary_pmc, 1));
 
+	map = primary_pmc->map;
+	if (map->acpi_pm_tmr_ctl_offset)
+		acpi_pmtmr_register_suspend_resume_callback(pmc_core_acpi_pm_timer_suspend_resume,
+							 pmcdev);
+
 	device_initialized = true;
 	dev_info(&pdev->dev, " initialized\n");
 
@@ -1471,6 +1510,12 @@ static int pmc_core_probe(struct platform_device *pdev)
 static void pmc_core_remove(struct platform_device *pdev)
 {
 	struct pmc_dev *pmcdev = platform_get_drvdata(pdev);
+	const struct pmc *pmc = pmcdev->pmcs[PMC_IDX_MAIN];
+	const struct pmc_reg_map *map = pmc->map;
+
+	if (map->acpi_pm_tmr_ctl_offset)
+		acpi_pmtmr_unregister_suspend_resume_callback();
+
 	pmc_core_dbgfs_unregister(pmcdev);
 	pmc_core_clean_structure(pdev);
 }

drivers/platform/x86/intel/pmc/core.h

@@ -68,6 +68,8 @@ struct telem_endpoint;
 #define SPT_PMC_LTR_SCC				0x3A0
 #define SPT_PMC_LTR_ISH				0x3A4
 
+#define SPT_PMC_ACPI_PM_TMR_CTL_OFFSET		0x18FC
+
 /* Sunrise Point: PGD PFET Enable Ack Status Registers */
 enum ppfear_regs {
 	SPT_PMC_XRAM_PPFEAR0A = 0x590,
@@ -148,6 +150,8 @@ enum ppfear_regs {
 #define SPT_PMC_VRIC1_SLPS0LVEN			BIT(13)
 #define SPT_PMC_VRIC1_XTALSDQDIS		BIT(22)
 
+#define SPT_PMC_BIT_ACPI_PM_TMR_DISABLE		BIT(1)
+
 /* Cannonlake Power Management Controller register offsets */
 #define CNP_PMC_SLPS0_DBG_OFFSET		0x10B4
 #define CNP_PMC_PM_CFG_OFFSET			0x1818
@@ -351,6 +355,8 @@ struct pmc_reg_map {
 	const u8  *lpm_reg_index;
 	const u32 pson_residency_offset;
 	const u32 pson_residency_counter_step;
+	const u32 acpi_pm_tmr_ctl_offset;
+	const u32 acpi_pm_tmr_disable_bit;
 };
 
 /**
@@ -424,6 +430,8 @@ struct pmc_dev {
 	u32 die_c6_offset;
 	struct telem_endpoint *punit_ep;
 	struct pmc_info *regmap_list;
+
+	bool enable_acpi_pm_timer_on_resume;
 };
 
 enum pmc_index {

drivers/platform/x86/intel/pmc/icl.c

@@ -46,6 +46,8 @@ const struct pmc_reg_map icl_reg_map = {
 	.ppfear_buckets = ICL_PPFEAR_NUM_ENTRIES,
 	.pm_cfg_offset = CNP_PMC_PM_CFG_OFFSET,
 	.pm_read_disable_bit = CNP_PMC_READ_DISABLE_BIT,
+	.acpi_pm_tmr_ctl_offset = SPT_PMC_ACPI_PM_TMR_CTL_OFFSET,
+	.acpi_pm_tmr_disable_bit = SPT_PMC_BIT_ACPI_PM_TMR_DISABLE,
 	.ltr_ignore_max = ICL_NUM_IP_IGN_ALLOWED,
 	.etr3_offset = ETR3_OFFSET,
 };

drivers/platform/x86/intel/pmc/mtl.c

@@ -462,6 +462,8 @@ const struct pmc_reg_map mtl_socm_reg_map = {
 	.ppfear_buckets = MTL_SOCM_PPFEAR_NUM_ENTRIES,
 	.pm_cfg_offset = CNP_PMC_PM_CFG_OFFSET,
 	.pm_read_disable_bit = CNP_PMC_READ_DISABLE_BIT,
+	.acpi_pm_tmr_ctl_offset = SPT_PMC_ACPI_PM_TMR_CTL_OFFSET,
+	.acpi_pm_tmr_disable_bit = SPT_PMC_BIT_ACPI_PM_TMR_DISABLE,
 	.lpm_num_maps = ADL_LPM_NUM_MAPS,
 	.ltr_ignore_max = MTL_SOCM_NUM_IP_IGN_ALLOWED,
 	.lpm_res_counter_step_x2 = TGL_PMC_LPM_RES_COUNTER_STEP_X2,

drivers/platform/x86/intel/pmc/spt.c

@@ -130,6 +130,8 @@ const struct pmc_reg_map spt_reg_map = {
 	.ppfear_buckets = SPT_PPFEAR_NUM_ENTRIES,
 	.pm_cfg_offset = SPT_PMC_PM_CFG_OFFSET,
 	.pm_read_disable_bit = SPT_PMC_READ_DISABLE_BIT,
+	.acpi_pm_tmr_ctl_offset = SPT_PMC_ACPI_PM_TMR_CTL_OFFSET,
+	.acpi_pm_tmr_disable_bit = SPT_PMC_BIT_ACPI_PM_TMR_DISABLE,
 	.ltr_ignore_max = SPT_NUM_IP_IGN_ALLOWED,
 	.pm_vric1_offset = SPT_PMC_VRIC1_OFFSET,
 };

drivers/platform/x86/intel/pmc/tgl.c

@@ -197,6 +197,8 @@ const struct pmc_reg_map tgl_reg_map = {
 	.ppfear_buckets = ICL_PPFEAR_NUM_ENTRIES,
 	.pm_cfg_offset = CNP_PMC_PM_CFG_OFFSET,
 	.pm_read_disable_bit = CNP_PMC_READ_DISABLE_BIT,
+	.acpi_pm_tmr_ctl_offset = SPT_PMC_ACPI_PM_TMR_CTL_OFFSET,
+	.acpi_pm_tmr_disable_bit = SPT_PMC_BIT_ACPI_PM_TMR_DISABLE,
 	.ltr_ignore_max = TGL_NUM_IP_IGN_ALLOWED,
 	.lpm_num_maps = TGL_LPM_NUM_MAPS,
 	.lpm_res_counter_step_x2 = TGL_PMC_LPM_RES_COUNTER_STEP_X2,